Method for compressing gases using same gas as working fluid

ABSTRACT

A method of compressing gas using the same gas as the working fluid, using a compressor comprising a reciprocating piston type compressor, a driving cylinder and a driven cylinder. The piston type compressor receives low pressure gas and fills the driven cylinder to a medium pressure target. A valve then directs the output from the piston type compressor to fill the driving cylinder, creating sufficient force to drive the connecting rod between the cylinders fully toward the driven cylinder. The connecting rod force compresses the gas in the driven cylinder and forces it out through a one way valve to a storage cylinder. A valve then directs the piston type compressor to fill the opposite side of the driving cylinder and the driven cylinder, forcing the connecting rod to retract. This cycle is repeated until the final output target high pressure is achieved in the storage vessel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional patent application No. 61/588,237, filed Jan. 19, 2012 by the present inventors.

BACKGROUND

1. Field

This application relates to the compressing of gases such that a low pressure gas is compressed to a high pressure gas. The compressor methods and apparatus described herein may be used for natural gas storage for natural gas powered motor vehicles.

2. Prior Art

Traditionally, multistage reciprocating piston type compressors have been used to compress gases. These piston type compressors are efficient at compressing low-to-medium level pressures. These compressors typically rotate at high speeds and employ oiless designs to eliminate oil in the compressed gas stream. Oil in the gas stream has known detrimental effects to injectors and valves. These piston type compressors suffer from high heat buildup and reduced longevity due to their oiless design.

More recently, hydraulic-based gas compressors are being used due to several advantages; these compressors operate at much slower rates thus producing less heat, have long life due to the lubricating effect of the hydraulic oil, and do not tend to aspirate oil into the gas like reciprocating piston type compressors.

There are many hydraulic-based compressors described in prior art that use a motor or engine driven hydraulic pump to produce high pressure fluid. The high pressure fluid is the working medium used to then compress a gas. Prior art describes compression taking place in one or more cylinders. Some embodiments include and some do not include a piston or other barrier to separate the gas and hydraulic fluid. Other art describes completely separate cylinders (one driving and one being driven) connected by a common rod.

Because many gases occur or are delivered at very low pressures (<5 psi), some prior art hydraulic based gas compressors describe the use of a pre-compressor to increase the gas from very low pressure to a medium pressure (15-200 psi) before hydraulic based compressing to the final high pressure (>2500 psi).

Hydraulic based compressors hold many advantages over more traditional reciprocating piston based compressors such as decreased heat, maintenance, operating speeds and noise, along with increased longevity and output pressure capability.

The disadvantage of hydraulic based compressors is the decreased inefficiency inherent in not compressing the gas directly as in a reciprocating piston type compressor; first the hydraulic fluid must be compressed, then the high pressure fluid is used to impart high pressure on the gas itself. This extra process step creates inefficiencies of energy transfer to the final desired product, a compressed gas. Hydraulics are also prone to small oil leaks that form on many fittings, seals and valves that collect dust, which it turns captures heat. Hydraulic based compressors are often more expensive to manufacture because of the extra pump, hoses, valves, controls and fluid storage and cooling equipment associated with hydraulic equipment.

SUMMARY

In accordance with one embodiment, a better method to compress gases is to use the same gas being compressed as the working medium that also does the compressing. This method offers all the advantages of hydraulic-based gas compression with greater efficiency, less equipment, no hydraulic leaks, and lower manufacturing costs.

DRAWINGS—FIGURES

FIG. 1 is a pictorial view of one embodiment of a compressor system according to the present invention, illustrating a single medium pressure reciprocating piston type compressor with one driving and one driven cylinder.

FIG. 2 is a pictorial view of one embodiment of a compressor system according to the present invention, illustrating a single medium pressure reciprocating piston type compressor and multiple (2 shown) driving and one driven cylinder.

FIG. 3 is a pictorial view of one embodiment of a compressor system according to the present invention, illustrating a single medium pressure reciprocating piston type compressor and one double ended driving and two driven cylinders.

FIG. 4 is a pictorial view of one embodiment of a compressor system according to the present invention, illustrating an integrated driving and driven cylinder arrangement.

FIG. 5 is a pictorial view of one embodiment of a compressor system according to the present invention, illustrating the use of multiple medium pressure reciprocating piston type compressors. Compressor systems with 2 and 3 compressors are shown.

DRAWINGS - REFERENCE NUMERALS 101 low pressure 102 check valve 103 piston type gas input compressor 104 electric clutch 105 valve 106 driving cylinder 107 connecting rod 108 position 109 driven cylinder sensor 110 pressure sensor 111 controller 112 high pressure gas outlet 113 motor or engine 114 pulley 115 belts or chain

DETAILED DESCRIPTION First Embodiment—FIG. 1

One embodiment of a gas compressor system is illustrated in FIG. 1. This system has a low pressure input 101 where the gas that will be compressed and used to accomplish compression enters. A check valve 102 insures compressed gas does not flow back to input 101. A motor or engine 113 drives an intermediate-pressure piston type compressor 103 through a belt, chain or coupling 115. Compressor 103 has an electric clutch 104 that allows disabling/enabling compressing without turning off engine/motor 113. Driving cylinder 106 is connected to driven cylinder 109 via a connecting rod 107. Intermediate-pressure working gas from compressor 103 is controlled by valve 105 to allow back and forth actuation of driving cylinder 106. Check valve 102 a allows passage of intermediate-pressure gas to fill driven cylinder 109 and restricts high-pressure compressed gas exiting driven cylinder 109. Several types of common cylinder position sensors 108, 108 b, 108 c detect cylinder position. Check valve 102 b allows passage of high-pressure compressed gas exiting driven cylinder 109 and restricts intermediate-pressure compressed gas that has exited compressor 103. Pressure gages 110, 110 a, 110 b send pressure levels to Control/Process/HMI electronics 111. Control/Process/HMI electronics 111 monitors the compression process, temperatures, inputs and outputs and provides compressor status to the user.

Operation First Embodiment—FIG. 1

An engine/motor 113 drives piston compressor 103 by an enabled electric clutch 104. During this ‘filling stroke’, gas is drawn from input 101 through check valve 102 and valve 105 into the right hand sides of driving 106 and driven 109 cylinders. When position sensors 108, 108 b, 108 c sense that the cylinder stroke is complete and pressure reaches the desired level at gage 101 a, the filling stroke is complete. The ‘compression stroke’ then begins when control electronics 111 directs valve 105 to shift position to direct intermediate-pressure gas from compressor 103 into the left side of driving cylinder 106. The driving cylinder connecting rod 107 is forced to the right, compressing the gas trapped on the right side of driven cylinder 109. High-pressure gas flows out through check valve 102 b and into a connected external storage tank (or on board vehicle tank) connected to high-pressure outlet 112. Compressed gas exiting driven cylinder 109 is blocked by check valve 102 a. Position sensor 108, 108 b, 108 c detects that the connecting rod 107 has travelled fully to the right completing a compression stroke. Control electronics 111 shifts valve 105 to begin another filling stroke. Control electronics 111 controls the repetition of filling and compression strokes until the pressure gage 110 b detects that the desired high pressure has been reached, completing the desired gas compression.

DESCRIPTION Alternative Embodiment—FIG. 2

An alternative embodiment of a compressor system is illustrated in FIG. 2. This embodiment is similar to embodiment in FIG. 1 but employs multiple driving cylinders 106, 106 a to increase the driving force exerted on driven cylinder 109, or to achieve the same force on driven cylinder 109 with a reduced working pressure requirement from compressor 103.

Operation Alternative Embodiment—FIG. 2

Operation is identical to the operation of the first embodiment except that in this embodiment multiple driving cylinders 106, 106 a (two shown) are being employed.

Operation Alternative Embodiment—FIG. 3

An alternative embodiment of a compressor system is illustrated in FIG. 3. This embodiment employs a double ended driving cylinder 106 connected to two driven cylinders 109, 109 a. One advantage of this embodiment is increased efficiency due to the fact that every stroke includes both a filling and compression stroke.

Operation Alternative Embodiment—FIG. 3

Operation is very similar to the operation of the first embodiment except that in this embodiment, with every stroke of the driving cylinder 106, both filling and compressing is occurring simultaneously. When the driving stroke is towards the right, right driven cylinder 109 a is performing compression and left driven cylinder 109 is being filled. When the driving stroke is towards the right, right driven cylinder 109 a is being filled and left driven cylinder 109 is performing compression.

DESCRIPTION Alternative Embodiment—FIG. 4

An alternative embodiment of the compressor system is illustrated in FIG. 4. This embodiment employs custom cylinders that are co-located within an envelope. FIG. 4 shows one driving section 106 and two driven cylinders 109, 109 a, but other quantities of driving and driven cylinder sections can be employed.

OPERATION Alternative Embodiment—FIG. 4

Operation is identical to the embodiment described in FIG. 3. One possible advantage is increased gas containment, as any connecting rod seal leaks are contained within the envelope. Efficiency and longevity are also increased due to fewer parts.

DESCRIPTION Alternative Embodiment—FIG. 5

An alternative embodiment of the compressor system's piston-type compressor subsystem is illustrated in FIG. 5. This embodiment employs multiple intermediate-pressure compressors 103, 103 a, 103 b, 103 c, 103 d to share the work load. Compressor subsystems with 2 and 3 compressors are shown, but additional compressors can be added as desired.

OPERATION Alternative Embodiment—FIG. 5

Control electronics 111,111 a enables and disables compressors as needed based on various inputs such as incoming gas availability, temperature of compressors and desired gas compression rate. Compressors 103, 103 a, 103 b, 103 c, 103 d are enabled by energizing electric clutches 104, 104 a, 104 b, 104 c, 104 d. Rotational force is supplied by engine/motor 113, 113 a while pulley 114, 114 a supplies tension to belt/chain 115, 115 a.

CONCLUSIONS, RAMIFICATIONS, AND SCOPE

Accordingly the reader will see that, according to one embodiment of the invention, I have provided a gas compressor method and apparatus that combines the advantages of traditional reciprocating piston type compressors with the advantages of hydraulic-based compressors. These advantages are accomplished by employing the same gas being compressed (the final product) as the working medium to accomplish compression.

While the above description contains many specificities, these should not be construed as limitations on the scope of any embodiment, abut as exemplifications of the presently preferred embodiments thereof. Many other ramifications and variations are possible within the teachings of the various embodiments. For example, the cylinders described can be increased or decreased in volume to meet the desired compressed gas output. The quantity of driving and driven cylinders can be increased or decreased to meet a desired balance between volume and pressure of the compressed gas and working medium pressure requirements. The driving and driven cylinders can be connected directly or through the use of mechanisms to increase the mechanical advantage. The driving and driven cylinders can be manufactured in many different shapes to meet mechanical or packaging constraints or requirements.

Thus the scope of the invention should be determined by the appended claims and their legal equivalents, and not by the examples given. 

We claim:
 1. A method for compressing a compressible gas using the same gas being compressed as the working medium that also does the compressing, using an apparatus comprising a medium-pressure compressor, a larger driving cylinder, and a smaller driven cylinder, comprising: repeating a filling and compression cycle while sufficient gas supply is available and a pressure measured by an output pressure sensing means is below an output target pressure; and allowing passage of high-pressure compressed gas exiting from said driven cylinder and entering a storage location during a compression cycle by a one-way check valve; and blocking of said high-pressure compressed gas by a one-way check valve during said compression cycle from returning to a reciprocating control valve and said larger driving cylinder; and controlling of reciprocating control valve by a electronic controller means such that of medium-pressure compressed causes repeated reciprocation of said larger driving cylinder; and monitoring stroke position signals from cycle stroke position sensor means to said electronics controller; and drawing in of low-pressure gas from a gas source through a one-way check valve into said medium- pressure compressor; and outputting said medium-pressure gas used as both the compressing force in said larger driving cylinder and the pre-compressed gas flowing into said smaller driven cylinder; and rotating of said medium-pressure compressor to produce said medium-pressure gas; and monitoring and controlling of the compressor cycle, and reporting the compressor status and compressing progress by said electronic controller means; and terminating said filling and compression cycle when a pressure measured by an output pressure sensing means reaches said output target pressure.
 2. Apparatus for compressing a compressible gas as using the same gas being compressed as the working medium that also does the compressing, comprising: a. a one-way check valve allowing high-pressure compressed gas exiting from a driven cylinder during a compression cycle, and b. a second one-way check valve blocking high-pressure compressed gas from flowing towards back towards a reciprocating control valve and a larger driving cylinder, and c. said reciprocating control valve controlling the passage of medium-pressure compressed gas in order to cause repeated reciprocation of said larger driving cylinder, and d. a means of sensing cycle stroke position sensors, and e. said medium-pressure compressor drawing in low-pressure gas from a gas source through a one-way check valve and outputting said medium-pressure gas used as both the compressing force in said larger driving cylinder and the pre-compressed gas flowing into said smaller driven cylinder, and f. a means for conveying rotational energy to the said medium-pressure compressor, and g. a means of controlling, monitoring, and reporting the status of compressing progress. 3) The compressor of claim 2, wherein said driving cylinders comprises a plurality of said driving cylinders. 4) The compressor of claim 2, wherein said driven cylinders comprises a plurality of said driven cylinders. 5) The compressor of claim 2, wherein said medium-pressure compressors comprises a plurality of said medium-pressure compressors. 6) The compressor of claim 2, wherein said medium-pressure compressors comprises a multiple number of medium-pressure compressors capable of being enabled or disabled. 7) The compressor of claim 2, wherein said driving cylinders comprises a double-ended driving cylinder providing for simultaneous filling and compressing events of attached said driven cylinder(s). 8) The compressor of claim 2, wherein said medium-pressure compressors is of the air conditioning type compressor. 9) The compressor of claim 2, wherein said medium-pressure compressors is of the scuba type air compressor. 10) The compressor of claim 2, wherein said rotational energy driving said medium-pressure compressor is supplied by electric motor, petroleum, natural gas or propane powered engine. 11) The compressor of claim 2, wherein said driving cylinder(s) and said driven cylinder(s) comprises a said driving cylinder (s) and said driven cylinder(s) fabricated within a common envelope. 12) The compressor of claim 2, wherein said compressor system further including means of sensing sufficiency of said low pressure gas supply. 13) The compressor of claim 2, wherein said compressor system further including gas and equipment cooling apparatus. 